From the web page: Dragonfly is an in-memory data store built for modern application workloads. It is fully compatible with the Redis and Memcached APIs, required no code changes to adopt
Reproducibility and peace of mind! There's nothing worse that getting woken up at 3:30 AM and realizing that it'll probably take a few hours to rebuild a server because it's dead and not coming back.
When infrastructure is code, you just spin up a new machine...no thinking involved. Also, since you're used to deploying this way, the process is smooth and as quick possible.
When you build the server by hand...you're often searching around for old ssl certificates, installing packages you forgot were dependencies, etc. Takes a long time to get it right.
If you're skeptical of the cost/benefit of the approach, you realize really quick that it's worthwhile when stuff starts to fail. Especially if it happens more than once.
Check out enpass. Small, one time payment per platform. (Free for certain usage). It is a native client that supports sync. It also works well cross-platform, including linux. The mobile clients are also good.